First principle studies on the electronic structures and absorption spectra in KMgF₃ crystal with fluorine vacancy

详细信息    查看全文

• 作者：Fang Cheng ; Tingyu Liu ; Qiren Zhang ; Hailin Qiao ; Xiuwen Zhou
• 关键词：KMgF₃ crystal ; Ab initio calculations ; Defects ; Electronic structures ; Absorption spectra ; Fluorine ion vacancy
• 刊名：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
• 出版年：2010
• 出版时间：1 August 2010
• 年：2010
• 卷：268
• 期：15
• 页码：2403-2407
• 全文大小：457 K

文摘

The experiments indicate that the perfect KMgF₃ crystal has no absorption in the visible range, however the electron irradiation induces a complex absorption spectrum. The absorption spectra can be decomposed by five Gaussian bands peaking at 2.5 eV (488 nm), 3.4 eV (359 nm), 4.2 eV (295 nm), 4.6 eV (270 nm) and 5.2 eV (239 nm), respectively. The purpose of this paper is to seek the origins of the absorption bands. The electronic structures and absorption spectra either for the perfect KMgF₃ or for KMgF₃: with electrical neutrality have been studied by using density functional theory code CASTEP with the lattice structure optimized. The calculation results predicate that KMgF₃: also exhibits five absorption bands caused by the existence of the fluorine ion vacancy and the five absorption bands well coincide with the experimental results. It is believable that the five absorption bands are related to in KMgF₃ crystal produced by the electron irradiation.